This is a note to let you know that I've just added the patch titled
usb: gadget: f_fs: Fix use-after-free
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 38740a5b87d53ceb89eb2c970150f6e94e00373a Mon Sep 17 00:00:00 2001
From: Lars-Peter Clausen <lars@xxxxxxxxxx>
Date: Thu, 14 Apr 2016 17:01:17 +0200
Subject: usb: gadget: f_fs: Fix use-after-free
When using asynchronous read or write operations on the USB endpoints the
issuer of the IO request is notified by calling the ki_complete() callback
of the submitted kiocb when the URB has been completed.
Calling this ki_complete() callback will free kiocb. Make sure that the
structure is no longer accessed beyond that point, otherwise undefined
behaviour might occur.
Fixes: 2e4c7553cd6f ("usb: gadget: f_fs: add aio support")
Cc: <stable@xxxxxxxxxxxxxxx> # v3.15+
Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
---
drivers/usb/gadget/function/f_fs.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index e21ca2bd6839..15b648cbc75c 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -646,6 +646,7 @@ static void ffs_user_copy_worker(struct work_struct *work)
work);
int ret = io_data->req->status ? io_data->req->status :
io_data->req->actual;
+ bool kiocb_has_eventfd = io_data->kiocb->ki_flags & IOCB_EVENTFD;
if (io_data->read && ret > 0) {
use_mm(io_data->mm);
@@ -657,13 +658,11 @@ static void ffs_user_copy_worker(struct work_struct *work)
io_data->kiocb->ki_complete(io_data->kiocb, ret, ret);
- if (io_data->ffs->ffs_eventfd &&
- !(io_data->kiocb->ki_flags & IOCB_EVENTFD))
+ if (io_data->ffs->ffs_eventfd && !kiocb_has_eventfd)
eventfd_signal(io_data->ffs->ffs_eventfd, 1);
usb_ep_free_request(io_data->ep, io_data->req);
- io_data->kiocb->private = NULL;
if (io_data->read)
kfree(io_data->to_free);
kfree(io_data->buf);
--
2.8.0
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